Coiled gas discharge tubes for gas discharge lamps

Abstract

A gas discharge tube (e.g., a lighting tube) comprising two coiled segments is described. The geometry of the coiled segments is such that the angle of the tangent to the center line of the tube with respect to the tube's longitudinal axis gradually increases as one moves upward along the ascending coiled segment, and gradually decreases as one moves down the descending coiled segment.

I claim: 
     
       1. A coiled glass tube assembly for use in a compact flourescent lamp, the exterior surfaces of the tube assembly defining a center line extending throughout said coiled glass tube assembly, said tube assembly comprising: an upwardly rising glass coil portion, a downwardly descending glass coil portion, and a terminal loop portion joined to an upper end of said rising coil portion at a first transition point, said terminal loop portion also joined to an upper end of said descending coil portion at a second transition point;   a longitudinally-extending center axis defined by said upwardly rising coil portion and said downwardly descending coil portion, said axis passing through the midpoint of said terminal loop portion;   the shape of the coiled glass tube assembly characterized by the fact that the tangent of the angle formed by the intersection of the tube assembly center line and the longitudinal axis with reference to a plane located beneath the rising and descending coil portions and perpendicular to said longitudinal axis has: a) a positive value in said upwardly rising glass coil portion,   b) a larger positive value between said first transition point and the point of intersection of the longitudinal axis and the loop portion midpoint,   c) a value of zero at the point of intersection of the longitudinal axis and the loop portion midpoint,   d) a negative value between said intersection point and said second transition point, and   e) a smaller negative value in said downwardly descending glass coil portion; and     an electrode at a sealed lower end of said rising coil portion and an electrode at a sealed lower end portion of said descending coil portion.   
     
     
       2. A coiled glass tube assembly for use in a compact flourescent lamp, the exterior surfaces of the tube assembly defining a center line extending throughout said coiled glass tube assembly, said tube assembly comprising: an upwardly rising glass coil portion, a downwardly descending glass coil portion, and a terminal loop portion joined to an upper end of said rising coil portion at a first transition point, said terminal loop portion also joined to an upper end of said descending coil portion at a second transition point;   a longitudinally-extending center axis defined by said upwardly rising coil portion and said downwardly descending coil portion, said axis passing through the midpoint of said terminal loop portion;   the shape of the coiled glass tube assembly characterized by the fact that the tangent of the angle formed by the intersection of the tube assembly center line and the longitudinal axis with reference to a plane located beneath the rising and descending coil portions and perpendicular to said longitudinal axis has: a) a positive value in said upwardly rising glass coil portion,   b) a larger positive value between said first transition point and the point of intersection of the longitudinal axis and the loop portion midpoint,   c) a value of zero at the point of intersection of the longitudinal axis and the loop portion midpoint,   d) a negative value between said intersection point and said second transition point, and   e) a smaller negative value in said downwardly descending glass coil portion; and     an electrode at a sealed lower end of said rising coil portion and an electrode at a sealed lower end portion of said descending coil portion.